In the field of radar design there is an ever existing emphasis on increasing both the detection and identification capability of the radar. This has lead to designs utilizing narrower and narrower pulses of transmitted electromagnetic energy to break out more features (i.e., increase the resolution) associated with a target. However, narrow pulse systems are prohibitively expensive, especially baseband pulse systems.
One solution which increases the radar system's detection capability utilizes a polarization diverse antenna systems capable of transmitting and receiving pulses of various polarizations. In practice however, these systems are often very complex, unacceptably heavy and physically too large for use in airborne applications. As an example, U.S. Pat. No. 3,720,947 assigned to the United States government discloses a mechanical switching system for changing the polarization of a radar antenna to either a linear, circular right or circular left polarization. This mechanical switching system is not compatible with recent requirements for airborne radar systems, especially a fighter aircraft radar system. In addition, the mechanical switching system is too slow to allow a radar system to switch polarization on a pulse to pulse basis.
One way to provide a polarization diverse radar system is to provide a lens in front of a radar antenna to switch the polarization of the radiated and received electromagnetic waveform to the desired polarization. U.S. Pat. No. 4,901,086 assigned to the Raytheon Company discloses a radar system incorporating a lens which transforms a linearly polarized waveform to a circularly polarized waveform on transmit, and transforms a circularly polarized waveform to a linearly polarized waveform on receive. However, this system does not have the flexibility to vary the polarization of the transmit and receive waveforms on demand, or pulse to pulse.